It is well known in the art that a binder, generally an adhesive, may be used to stabilize filamentary structure packages such as metal wire coils, electrical cable packages, etc. In some applications, which require payout of the wound filament from the package, the adhesive is used not only to stabilize the package, but also to control the fluent payout of the filament, and to protect the filament for long life durability. An example of such an application is an optical fiber dispenser at the tail of a guided missile, in which optical fiber conveys navigation signals to the missile, or an optical fiber dispenser which is used in a similar way, but conveys optical signals between the target and the control station.
Optical fiber packages, particularly canisters, viz. assemblies of a bobbin and superimposed layers of fibers wound thereon, are usually obtained by winding.
In order to stabilize the canisters, an adhesive binder is usually applied to the fiber or to each fiber layer. The binder usually has adhesive properties, which are useful for such a purpose. However, the binder must also contribute to solving other problems encountered in preparing and using optical fiber canisters. Some such problems refer to the winding operation, including winding faults, small gaps, voids and the like.
However, particularly serious problems are met with when the fiber has to be unwound or paid out from the canister. When the fiber is unwound, it is found that prior art adhesives adhere to the fiber too strongly, or in fragments. This causes increased wind resistance or local impacts when the fiber is deployed, thus creating a corresponding tension or bending in the fiber, which might cause stress concentration and possible breakages thereof, which means a total failure of the system. Furthermore, an incompatible adhesive binder may cause damages to the fiber during storage and payout, causing increased optical loss in the fiber, or causing damage such as crazing due to stress corrosion.
It may be said that contradictory properties are required from an optical fiber adhesive binder. On one hand it must have sufficient adhesive strength and durability to hold the fiber in place during long storage without maintenance, flight and unwinding operation. On the other hand, it must not interfere with the fiber unwinding and, while holding the fiber layers in place, must allow the fiber to be paid out from the package easily and regularly.
Several polymers are known in the prior art as adhesive binders for optical fiber packages. A different adhesive composition is described in Israeli Patent 92130, which comprises 5% of an adhesive consisting of one-fourth of 3,3,3-trifluoropropylmethylsiloxane and three-fourths of a polydimethylsiloxane, and 95% of a carrier which is a trichlorotrifluoroethane or a trichloroethane or a mixture thereof.
It is a purpose of this invention to eliminate the drawbacks of the prior art optical fiber adhesive binders.
It is another purpose of this invention to provide an adhesive binder which permits to carry out the payout of optical fiber canisters at high speed.
It is a further purpose of this invention to provide an adhesive binder which can be applied either continuously to the optical fiber or to the fiber layers during the winding operation.
It is a still further purpose of this invention to provide an adhesive binder that is particularly adapted for the winding and payout of optical fibers on and from canisters for guided objects, such as missiles, etc.
Other purposes and advantages of the invention will appear as the description proceeds.